diff --git a/Components/1770/1770.cpp b/Components/1770/1770.cpp
index d465c3578..a725a4770 100644
--- a/Components/1770/1770.cpp
+++ b/Components/1770/1770.cpp
@@ -535,7 +535,7 @@ void WD1770::posit_event(Event new_event_type)
 		}
 		if(distance_into_section_ == 7)
 		{
-			printf("Considering %d/%d\n", header_[0], header_[2]);
+			printf("Considering %d/%d at %0.4f\n", header_[0], header_[2], get_time_into_track().get_float());
 			is_reading_data_ = false;
 			if(header_[0] == track_ && header_[2] == sector_ &&
 				(has_motor_on_line() || !(command_&0x02) || ((command_&0x08) >> 3) == header_[1]))
@@ -563,6 +563,7 @@ void WD1770::posit_event(Event new_event_type)
 			});
 			distance_into_section_ = 0;
 			is_reading_data_ = true;
+			printf("\n");
 			goto type2_read_byte;
 		}
 		goto type2_read_data;
@@ -570,7 +571,7 @@ void WD1770::posit_event(Event new_event_type)
 	type2_read_byte:
 		WAIT_FOR_EVENT(Event::Token);
 		if(latest_token_.type != Token::Byte) goto type2_read_byte;
-		data_ = latest_token_.byte_value;
+		data_ = latest_token_.byte_value; printf("%02x", data_);
 		update_status([] (Status &status) {
 			status.lost_data |= status.data_request;
 			status.data_request = true;
@@ -579,6 +580,7 @@ void WD1770::posit_event(Event new_event_type)
 		if(distance_into_section_ == 128 << header_[3])
 		{
 			distance_into_section_ = 0;
+			printf("\n");
 			goto type2_check_crc;
 		}
 		goto type2_read_byte;
@@ -640,9 +642,10 @@ void WD1770::posit_event(Event new_event_type)
 
 		WAIT_FOR_EVENT(Event::DataWritten);
 		distance_into_section_ = 0;
+		printf("\n");
 
 	type2_write_loop:
-		write_byte(data_);
+		write_byte(data_); printf("%02x", data_);
 		update_status([] (Status &status) {
 			status.data_request = true;
 		});
@@ -650,6 +653,7 @@ void WD1770::posit_event(Event new_event_type)
 		distance_into_section_++;
 		if(distance_into_section_ == 128 << header_[3])
 		{
+			printf("\n");
 			goto type2_write_crc;
 		}
 
diff --git a/Storage/Disk/DiskController.cpp b/Storage/Disk/DiskController.cpp
index 5c61311fe..47c971a22 100644
--- a/Storage/Disk/DiskController.cpp
+++ b/Storage/Disk/DiskController.cpp
@@ -166,11 +166,15 @@ void Controller::end_writing()
 
 	if(!patched_track_)
 	{
-		// TODO: is the track already actually a patched track?
-		// see dynamic_pointer_cast
-		patched_track_.reset(new PCMPatchedTrack(track_));
+		// Avoid creating a new patched track if this one is already patched
+		patched_track_ = std::dynamic_pointer_cast<PCMPatchedTrack>(track_);
+		if(!patched_track_)
+		{
+			patched_track_.reset(new PCMPatchedTrack(track_));
+		}
 	}
 	patched_track_->add_segment(write_start_time_, write_segment_);
+	invalidate_track();	// TEMPORARY: to force a seek
 }
 
 #pragma mark - PLL control and delegate
diff --git a/Storage/Disk/DiskController.hpp b/Storage/Disk/DiskController.hpp
index a39b74b48..19e9e8755 100644
--- a/Storage/Disk/DiskController.hpp
+++ b/Storage/Disk/DiskController.hpp
@@ -110,6 +110,7 @@ class Controller: public DigitalPhaseLockedLoop::Delegate, public TimedEventLoop
 		void step(int direction);
 		virtual bool get_drive_is_ready();
 		bool get_drive_is_read_only();
+		Time get_time_into_track();
 
 	private:
 		Time bit_length_;
@@ -135,7 +136,6 @@ class Controller: public DigitalPhaseLockedLoop::Delegate, public TimedEventLoop
 		Time cycles_per_bit_;
 
 		void setup_track();
-		Time get_time_into_track();
 };
 
 }
diff --git a/Storage/Disk/PCMPatchedTrack.cpp b/Storage/Disk/PCMPatchedTrack.cpp
index 71ef0de86..a70ec9da9 100644
--- a/Storage/Disk/PCMPatchedTrack.cpp
+++ b/Storage/Disk/PCMPatchedTrack.cpp
@@ -43,8 +43,7 @@ void PCMPatchedTrack::add_segment(const Time &start_time, const PCMSegment &segm
 
 	// the vector may have been resized, potentially invalidating active_period_ even if
 	// the thing it pointed to is still the same thing. So work it out afresh.
-	active_period_ = periods_.begin();
-	while(active_period_->start_time > current_time_) active_period_++;
+	insertion_error_ = current_time_ - seek_to(current_time_);
 }
 
 void PCMPatchedTrack::insert_period(const Period &period)
@@ -155,7 +154,8 @@ Track::Event PCMPatchedTrack::get_next_event()
 		else event = underlying_track_->get_next_event();
 
 		// see what time that gets us to. If it's still within the current period, return the found event
-		Time event_time = current_time_ + event.length - period_error;
+		Time event_time = current_time_ + event.length - period_error - insertion_error_;
+		insertion_error_.set_zero();
 		if(event_time < active_period_->end_time)
 		{
 			current_time_ = event_time;
diff --git a/Storage/Disk/PCMPatchedTrack.hpp b/Storage/Disk/PCMPatchedTrack.hpp
index 83182b39b..2ea8ffd04 100644
--- a/Storage/Disk/PCMPatchedTrack.hpp
+++ b/Storage/Disk/PCMPatchedTrack.hpp
@@ -52,7 +52,7 @@ class PCMPatchedTrack: public Track {
 		};
 		std::vector<Period> periods_;
 		std::vector<Period>::iterator active_period_;
-		Time current_time_;
+		Time current_time_, insertion_error_;
 
 		void insert_period(const Period &period);
 };